BACKFIRE

[1986GMCSierra]

My stock 1986 GMC 305 has a high idle problem and after she gets warmed up she backfires uncontrollably... i was thinkin the timing might br off a little but that doesnt fix the high idle.. Need help guys. thanks

[78BIG-TEN]

Choke being stuck could cause the high idle and also deliver to much fuel and
fouled the plugs causing your backfire

[Irish_Alley]

wheres it backfiring out of? but high idle could be a vacuum leak, the vacuum lean would cause a lean condition and the lean condition might lead to higher temps and cause pre detonation? again this is 100% a guess but might be plausible

[1986GMCSierra]

wheres it backfiring out of? but high idle could be a vacuum leak, the vacuum lean would cause a lean condition and the lean condition might lead to higher temps and cause pre detonation? again this is 100% a guess but might be plausible

its coming out of my exhaust if thats what you mean?

[rich weyand]

Check your timing and that the distributor is clamped down tight.  Temperature changes in the winter can loosen a marginally tightened distributor, which will then rotate with the rotor shaft to a more retarded setting.  Retard it enough, and you will get backfires (actually, afterfires, since they are coming out the exhaust, not the carb).

[1986GMCSierra]

Check your timing and that the distributor is clamped down tight.  Temperature changes in the winter can loosen a marginally tightened distributor, which will then rotate with the rotor shaft to a more retarded setting.  Retard it enough, and you will get backfires (actually, afterfires, since they are coming out the exhaust, not the carb).

ok i will check my distributor thanks